186 



Mr. E. Scliunck. 



paler, though still showing tlie characteristic absorption-bands, while 

 in the solution of the ferrous compound only a faint indication of the 

 band in the red could be seen, the solution of the cupric compound 

 remaining quite unchanged as regards intensity of colour and distinct- 

 ness of absorption. After a still further exposure the absorption- 

 bands of the phyllocyanin solution had nearly disappeared, only a 

 faint indication of the one in the red remaining, but no change could 

 be perceived in the solution of the cupric compound. It appears, 

 therefore, that while the zinc compound shows far less stability 

 when exposed in solution to the action of air and light than uncom- 

 bined phyllocyanin, being indeed almost as unstable as chlorophyll 

 itself, the cupric compound is far more stable, the ferrous compound 

 occupying in this respect a position intermediate between that of the 

 zinc compound and that of uncombined phyllocyanin. There are 

 few compounds of colouring matters which would withstand the 

 combined action of light and oxygen for so long a period as phyllo- 

 cyanin cupric acetate. The instability of the zinc compound must 

 be due to the nature of the compound itself, for it is difficult to 

 suppose that the metallic base can in any way assist in the process of 

 oxidation, for such the process must be. 



Action of Caustic Alkali and Zinc on Phyllocyanin. — When phyllo- 

 cyanin is treated with boiling caustic potash lye to which zinc powder 

 is added, it dissolves rapidly, yielding a dark greenish-blue solution, 

 which after nitration from the excess of zinc, gives with acetic acid 

 a green precipitate. This precipitate, after nitration and washing, 

 dissolves in ether, giving a fine bluish-green fluorescent solution, 

 which resembles the solutions of phyllocyanin zinc acetate, but shows 

 a slightly different spectrum, all the bands except the first being 

 further away from the red. The ethereal solution leaves on spon- 

 taneous evaporation an amorphous residue, which is green by trans- 

 mitted, purple by reflected light. When instead of acetic acid hydro- 

 chloric acid is added to the greenish-blue alkaline solution, there is a 

 dark green precipitate, which differs from phyllocyanin inasmuch as 

 its ethereal solution is greener and far more fluorescent than an 

 ethereal solution of the latter, and shows a spectrum of five bands, 

 all of which lie further away from the red than the corresponding 

 ones of phyllocyanin. It is probable that the precipitate with hydro- 

 chloric acid consists of a product formed by the reducing action of 

 zinc on phyllocyanin, whereas the precipitate with acetic acid repre- 

 sents the double compound of this body with zinc and acetic acid, 

 being formed when acetic acid is added to the solution containing the 

 product of reduction along with zinc oxide. 



Action of Hydrochloric Acid and Metallic Tin on Phyllocyanin. — 

 When metallic tin is added to a solution of phyllocyanin in concen- 

 trated hydrochloric acid, the solution on standing gradually loses its 



